Added reference links for collection and environment to the readme
Added reference links for collection and environment to the readme

gituser4/Newman,mojowebdev/newman,cdanielsen/newman,xjodoin/newman,viig99/Newman,marcelotoledo5000/newman,digital-abyss/Newman,cerdman/newman,NeilCross/Newman-nogyp,prakhar1989/Newman,lorneb/newman,murugespandian/newman,ratpik/Newman,wcandillon/newman,SamvelRaja/newman,postmanlabs/newman,postmanlabs/newman,cdanielsen/newman,neillboyd/Newman